Data Modeling[Comparison of data modeling

techniques ]

By Renjini

Sindhuri

Contents

Introduction E-R modeling

Peter Chen Information Engineering Barkers Notation IDEFIX

UML modeling XML modeling

X- Entity modeling XUML

Conclusion

Introduction

Data modeling is the act of exploring data oriented structures.

Examines and compares different data modeling techniques

In the data modeling techniques we have traditional modeling and object oriented modeling of data

E-R modeling

It is a conceptual data model that views the real world as consisting of entities and relationships

It is used to transform relational tables that are easy to understand that enables easy communication with the end user

Peter –Chen developed E-R model

Peter –Chen notation

Entities are represented in the squared cornered and circles as attributes

Many –Many relationships can be represented without associative entity

Relationship itself has attributes and are considered as objects

It failed to represent unique identifier

Peter Chen’s Model

Information Engineering model

Developed by Clive Finkelstein Entities are represented in the squared cornered and

attributes are not shown at all they are shown in a separate list called entity list

Relationships like mandatory 1 and many can be represented

Unique identifiers are not represented

Information Engineering model diagram

Barkers Notation

Adopted by Oracle corporation for its CASE method Entities can be represented by round cornered

rectangle Same entity can be represented for role an interaction

or another kind of association Relationship names are prepositions and not verbs Unique identifiers can be represented by hash marks

next to the attribute

Barkers Notation diagram

IDEFIX Notation

It is a modeling technique that is used by many branches of the United States Federal government

A relationship name is a verb IDEFIX shows subtypes as separate entity boxes IDEFIX permits multiple inheritance and multiple type

hierarchies

IDEFIX diagram

UML

UML is an object modeling technique It models object classes instead of entities In the object oriented world the relationships are called

as associations Cardinality and optionality in UML is conveyed by

characters or numbers Express in the form of more complex upper and

lower limits UML introduces a small flag that includes text

describing any business rules

UML diagram

XML Notation

Describing data and interchanging structured and unstructured data on the Internet

It is a universal language of data on web XML tags are used to create data structures XML documents have been widely used for

interchanging data between heterogeneous systems.

XML notation

An example of XML notation

http://www.essentialstrategies.com/publications/modeling/xml.htm

X-Entity model

Conceptual model of XML uses X entity model in order to represent additional features

The entity can be denoted by ‘E’ ({A1,….An},{R1,…Rm},{D1,….Dk}) Each attribute A is associated with a domain Dom(Ai)

Which specifies its value set

Cardinality is denoted by Card(Ai)=(min,max)

X entity model diagram

XUML

XUML comprises the characteristics of XML and UML2.

It is used to express the containment semantics more explicitly

Supporting the concept of Business Components Specifying the data dependencies in multiple context

XUML diagram

UML and XUML model of a book store

Comparison of data modeling techniques

S.No Modeling Technique

Peter Chen Information Engineering

IDEFIX Richard Barker’s notation

UML

1. Entities squared cornered and circles as attributes

Squared cornered, attributes are not shown at all.

Round or square cornered rectangle

Round cornered rectangle

Models object classes

2. Relationship Nouns. So the relationships can be represent as objects and has attributes

Verbs Verb or verb phrase

Preposition not verb

Associations

3. Constraints between relationships

Failed to represent the constraints directly exclusive or)

Can represent

Constraints exclusive or ,inclusive

Cannot represent

Can represent

Constraints exclusive or)

Can represent

Constraints exclusive or )

Comparison of Data modeling techniques

S.No Modeling Technique

Peter Chen Information Engineering

IDEFIX Richard Barker’s notation

UML

4. Cardinality Many to Many relationships can be represented between the entities without the associative entity

Can represent Can represent in different ways

Can represent zero or more ,atleast

at least one

up to many,up to one

relationships

express more complex upper limits, zero, 3, 6-7, or 9

5. Sub types/

Super Types Cannot represent the sub types and

super type

sub-types can be represented inside their super-type

box

Sub types can be represented as separate entity boxes separate from its super type.

sub-types can be represented inside their super-type box

Can represent

6. Unique Identifier

Cannot represent

Cannot represent

Represented in the form of

primary key

Represented in the form of hash next to

the attribute

Can represent

Comparison of Data Modeling techniques

S.No Modeling Technique

Peter Chen Information Engineering

IDEFIX Richard Barker’s notation

UML

7. Aggregation Cannot represent

Cannot represent

Cannot represent

Cannot represent

Can represent only binary aggregations

8. Business Rules /

Components

Cannot Represent

Cannot Represent

Cannot Represent

Cannot Represent

Can Represent

Comparison of Data Modeling techniques

S.No Modeling Technique

Peter Chen Information Engineering

IDEFIX Richard Barker’s notation

UML

9.

Aesthetic Simplicity Score

High Medium Low High High

10. Completeness Score

Low medium medium medium medium

11. Language Notation Score

medium medium low medium High

Advantages of XUML

XUML can express the containment semantics more accurately.

Support the concept of Business Component. Can specify the data dependencies in

multiple context.

Contd..

XUML is more expressive, precise and

understandable. More rigorous and accurate.

Conclusion

By comparing the aesthetic simplicity, completeness, language notation (relationship) Mr. Barker's notation is favorable for requirement analysis model

XML is used in recent trends it follows a standard format for representing structured and semi structured data on web

X-Entity model has the advantages of both XML schemas and extends the ER model so that it can explicitly represent important features of XML schemas

The distinctive features of XUML made this technique of data modeling the latest trend for conceptual modeling of data.

References

1. Conceptual Modeling of XML schemas, Bernadette Farias Losio,Ana Carolina Salgado , Year: 2003,Publisher: ACM

2. XML conceptual modeling with XUML, HongXing Liu HuaZhong University of Science and Technology, P. R. China, YanSheng Lu HuaZhong University of Science and Technology, P. R. China,Qing Yang Wuhan Uni Pages: 973 – 976, Year of Publication: 2006, Publisher: ACM Press

3. PETER PIN-SHAN CHEN, “The Entity Relationship Model-Toward a Unified View of Data” , Massachusetts Institute of Technology, ACM Transactions on Data base System Volume1, Issue 1,Publisher-ACM

4. Data modeling in the understanding database course: adding UML and XML modeling to the traditional content. Journal of Computing Sciences in Colleges, Volume 17, Issue 5 (April 2002)

References

5. Data Modeling101.

http://www.agiledata.org/essays/dataModeling101.html

6.A comparison of Data Modeling ,David C Hay,Essential Strategies

Inc,October 1999.